The conventional manner of flushing and recharging the coolant system of such an automobile engine historically involves the removal of a closure cap from a filler pipe extending upwardly from a top header of the radiator while the engine is stationary, and then permitting the cooling system to drain by gravity through a stop cock associated with a bottom header of the radiator.
The engine of the automobile cannot be operated during such an operation, in that the engine would overheat and possibly seize during the draining operation, and thus, turbulence cannot be introduced into the coolant during the draining operation, such as is essential to insure the flushing of particulate matter out from the system. Such particulate matter is the product of scaling, flaking, corrosion or the like within the cooling system. Further, as the draining is exclusively through the stop-cock, which itself is of relatively small diameter, the draining of the system by gravity proceeds in an entirely quiescent manner further mitigating against the flushing out of the system of heavier particles of particulate matter.
The coolant fluid of such systems, further, almost without exception is an admixture of water and a petroleum based anti-freeze additive such as ethylene glycol, the waste coolant drained from the system thus constituting a source of pollution in the event that it is discharged directly onto the ground, or, as in common practice, it is discharged directly into a sewer system.
Further, as the coolant fluid is discharged from the system in a relatively quiescent manner, no guarantee can be made that particulate matter that has settled and forms, or potentially forms, a blockage in any part of the system is satisfactorily removed as the coolant fluid as it is discharged from the system.
The drainage of the system by gravity further provides no guarantee that the system has been fully drained, in that pockets filled with coolant fluid can remain within reentrant portions of the cylinder block, and can be trapped in the core of the heating system by air locks, either exclusively or in combination with already existing blockages or partial blockages existing within the system.
The requirement for pressure flushing of the system has been previously recognized, and has been accomplished by pressure flushing the system with a turbulent flow of coolant fluid, which, instead of being discharged from the stop cock associated with the bottom header, is discharged through the relatively large diameter opening of the filler pipe of the upper header.
As the cooling system is at no time emptied of coolant fluid during this procedure, the engine can be operated, as will be the water pump of the engine, thus promoting turbulence within the cooling system, but not necessarily of sufficient intensity to ensure scavenging of larger particles of particulate matter from the cooling system.
In order to introduce the turbulent supply of coolant fluid under pressure, one of the hoses between the cylinder block and the radiator is cut, and a tee fitting is inserted in that location, the supply of replacement coolant fluid under pressure being introduced into the branch of the tee fitting by an appropriate hose supplied from a power driven pump. Subsequent to the flushing operation the supply hose is removed from the branch of the tee fitting and the branch is capped leaving it available for a subsequent flushing operation.
In the flushing of the coolant system in this manner, there still is no guarantee that the entire cooling system will be flushed, in that the supply of flushing coolant fluid will take the path of least resistance between its point of insertion into the cooling system and its escape from the radiator filler tube.
This procedure allows the operation of the engine during the flushing procedure, and thus is far more successful than the previous procedure of gravity draining of the cooling system. However, as in the gravity drainage system, there is no guarantee that stagnant pockets of the cooling system will be flushed, and, that blockages or partial blockages will be removed. This is because the supply of coolant fluid under pressure cannot be constrained or redirected from its flow path of least resistance, and, uniformity of the flow of scavenging coolant fluid under pressure cannot be obtained throughout the entire system for the purpose of removing all existing particulate matter from within the cooling system. This applies particularly to the heating core, which usually is fed by convection in the absence of a separate pump for the coolant fluid heated in the cylinder block.